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Homework Help: Electrostatic rod homework

  1. Sep 30, 2008 #1
    1. A body will maintain a constant negative electrostatic charge if the body
    1) Maintains the same excess of electrons. 3) Continuously receives more electrons than it loses.
    I chose 3) but I think both choices work. However, the correct answer is 1), I don’t why 3) is wrong.

    2. Negatively charged rod A is used to charge rod B by induction. Object C is then charged by direct contact with rod B. The charge on object C
    1) is positive 3) is negative.
    I chose 3) because when negative charged rod A moves close to one end of rod B, the electrons in rod B would gather at the other end, so left the opposite end all positive. After that, when C comes to contact with rod B, it depends on which end it touches. I am little confused. If it touches the negative end, then C becomes negative; vice versa. But the answer was 1).

    thanks for help.
     
  2. jcsd
  3. Sep 30, 2008 #2

    LowlyPion

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    Re: electrostatic

    1. The operative word is Constant. Unchanging. Stays the same.

    2. If B's charge is affected by induction, it will be net positive and then it will be a sink for electrons when it is touched by C, imparting a net positive to C as well.
     
  4. Oct 1, 2008 #3
    Re: electrostatic

    But induction is not conduction, why B will be net positive? If B is positive orginally, it's still postive; if it's negative, it will still be negative.
     
  5. Oct 1, 2008 #4

    LowlyPion

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    Re: electrostatic

    A is negative. Induction makes B net positive. Touching neutral C to B makes C net positive too.
     
  6. Oct 2, 2008 #5
    Re: electrostatic

    If B is net positive, where did some electrons in B go?
     
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